1. Technical Field
The present invention relates particle image analyzers that seek information concerning particle size and shape by analyzing particle images.
2. Description of Related Art
In controlling the quality of fine ceramic, toner, pigment and abrasive powders, measuring and controlling particle diameter of the powders is extremely important. With recent advances in development and merchandizing of higher value-added powders, measurement of not only particle size but also shape parameters, as well as their quality control has become important. Moreover, maintaining quality in powder products necessitates measuring large particles and the aggregation of particles.
Herein, a particle image analyzer is known (Japan Laid-Open Pat. 08-136439) that within a flow cell transforms a particle-containing sample liquid into a sample flow by surrounding it with a sheath liquid. Sequentially capturing images of the sample flow and analytically processing the particle images obtained, the analyzer computes and displays a distribution diagram for particle diameter and shape parameters. The analyzer meanwhile enables computing the percentage of cohered particles by batch-displaying pictures of the imaged particles and classifying the particles. On the other hand, a flow cytometer is known (Japan Laid-Open Pat. 08-178826) that, based on signals from particles in a first flow region of a sample flow that flows down a sheath-flow cell, generates a distribution diagram for characteristic parameters of the various particles. The flow cytometer captures particles in a second flow region of the sample flow, and by designating coordinates in the distribution diagram, can display desired images.
Nevertheless, with the particle image analyzer in the former instance, it is difficult to display a desired image from among the large number of stored images. Furthermore, with the flow cytometer in the latter instance, particle images cannot be displayed by designating morphologically characterizing parameters.
The invention came about considering such circumstances, and an object therefore is to provide a particle image analyzer that facilitates displaying particle images by designating the particles on a distribution diagram for morphologically characterizing parameters.
A particle image analyzer of the present invention is characterized in that it is provided with: parameter computation means for computing at least one morphologically characterizing parameter for respective particle images obtained by image capture; storing means for storing particle images, morphologically characterizing parameters, and correlations between the particle images and the morphologically characterizing parameters with regard to the respective particle images; distribution-diagram generation means for generating a distribution diagram for morphologically characterizing parameters; designation means for designating an area within the distribution diagram; read-out means for reading out from the storing means particle images corresponding to morphologically characterizing parameters within the areas designated by the designation means; and display means for displaying the read-out particle images.
Morphologically characterizing parameters herein are parameters obtained by analyzing particle images. Parameters that can be employed include a particle diameter parameter indicating particle size, a circularity parameter indicating plus/minus roundness of the particles, and an aspect ratio (major/minor axis ratio) parameter indicating a vertical/horizontal ratio of the particles.
The distribution diagram may be a histogram (one-dimensional distribution diagram) wherein the parameter is a single of the morphologically characterizing parameters, or a scattergram (two-dimensional distribution diagram) wherein the parameters are a plurality, for example two, of the morphologically characterizing parameters.
The particle image analyzer preferably is also provided with a distribution analyzing means for analyzing distribution status of the morphologically characterizing parameters within the area designated by the designation means. Analyzing by the distribution analyzing means includes statistical analysis; and for example, with regard to particle diameter, circularity or aspect ratio, is the computation of analytical data such as arithmetic mean, standard deviation, coefficient of variation, median, mode, and 10%, 50% and 90% percentiles (cumulative percentages). Herein, xe2x80x9cpercentilexe2x80x9d indicates a value that is equivalent to cumulative percent when the cumulative frequency is taken to be 100%.
The particle image analyzer preferably is moreover provided with a classifying means for appending to the respective particle images classification information indicating particle status (such as primary particle, secondary particle and the aggregation of particles).
The respective particle images can be obtained by sequentially capturing particles on glass slides with a combined microscope and image-capturing device. Alternatively, the image pictures may be obtained from a particle image analyzer (Japan Laid-Open Pat. 08-136439) that obtains particle pictures by transforming a particle-containing sample liquid into a sample flow by surrounding it with a sheath liquid within a flow cell, and sequentially captures images of the sample flow.
The particles herein may be fine ceramic, toner, pigment, and abrasive and like industrial powders, and also may be particles such as erythrocytes, cells from cell cultures, microorganisms and plankton.
The parameter computation means for computing morphologically characterizing parameters for respective particle images obtained by image capture; the storing means for storing correlations between the particle images and the morphologically characterizing parameters with regard to the respective particle images; the distribution-diagram generation means for generating morphologically characterizing parameter distribution diagrams; the read-out means for reading out from the memory means particle images corresponding to morphologically characterizing parameters within the area designated by the designation means; the distribution analyzing means; and the classifying means can be configured in a image-processing circuit as well as a computer made up of a CPU, ROM, RAM and I/O port, or in a personal computer having image-processing functions.
The designation means for designating the area within the distribution diagram, furthermore, can designate by numerical value designations for the characterizing parameters and by enclosing the distribution diagram interior in arbitrary shapes, for which using a keyboard, mouse or like input means is preferable.
A display device such as a CRT or a liquid-crystal display, or a printing apparatus such as printer can be utilized as the display means for displaying the read-out particle images.
The present invention configured as above succeeds in facilitating display, since a user designates on a distribution diagram an image that the user desires to put up from among numerous stored images.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description in conjunction with the accompanying drawings.